Sig Miniplane - flat bottom or semi?
 

The sig site says semi sym but some threads here say it's flat bottom which causes less than stellar inverted perf. Did the kit change b/c the threads it seems are a couple yrs old?
Mike

RE: Sig Miniplane - flat bottom or semi?
 

I have a Smith Miniplane that I bought from a guy who got it from a guy.........So I don't know where it started, but the top wing is 58 inch, so It didn't come from the Sig kit. It could be a scratch built, as I have yet to see a kit with a 58 inch wing. But, to the point. It is semi sym. wing, both top and bottom. I had to rebuild the back 1/3, as the ups truck drove over the box it came in. Then recovered all, as old mono was brittle and broken and torn. It looks a lot better with the cowl on. But I am breaking in the motor.

Richard.

RE: Sig Miniplane - flat bottom or semi?
 

Built my second Smith last winter from Sig kit. It has a flat bottom wing. No problem with any flight charateristics.

RE: Sig Miniplane - flat bottom or semi?
 

looks like mini but no struts? definately bigger than the kit.
Mie

RE: Sig Miniplane - flat bottom or semi?
 

Thanks.. any issues with the landing gear.... posters say the balsa fairings crack as i guess would be expected.
Mike

RE: Sig Miniplane - flat bottom or semi?
 

Wing section is flat but the aft part curves up, so not quite Clark-Y section, very near semi-symetrical.

Gear fairings have tissue and dope covering, no problems.

RE: Sig Miniplane - flat bottom or semi?
 

EF,

That's a great looking Smith Mini! Fantastic job!

Mike

RE: Sig Miniplane - flat bottom or semi?
 

Thanks, I must say I realy enjoyed building and flying it, even if only 44" span. Truly rewarding.

One pic below shows part of the plan, where it can be seen that the airfoil is NOT flat bottom but actually semi-symmetrical.

RE: Sig Miniplane - flat bottom or semi?
 

EF,

What size 4-stroke engine do you have in the Mini?

Mike

RE: Sig Miniplane - flat bottom or semi?
 

An old (20 years?) OS 61 FS, and even though it's less powerful than when new, it's certainly enough.

RE: Sig Miniplane - flat bottom or semi?
 

An OS .52FS. Perfect IMHO

RE: Sig Miniplane - flat bottom or semi?
 

A .52 four stroker would be perfect. I agree.
I simply had the engine available and didn't want to buy a new one.

I flew my model again this morning, in quite windy weather, but it definitely has more power than necessary with the .61 FS.

RE: Sig Miniplane - flat bottom or semi?
 

EF,

Give us some detail on the covering and finishing of your Mini. It appears that you have some simulated pinking tape on the ribs. It looks great.

Mike

RE: Sig Miniplane - flat bottom or semi?
 

For covering I used Dave Brown Skyloft, and sanding sealer instead of the dope mentioned in the instructions.

I read many negative comments on this covering material, and I disagree with all of them.

I wanted a doped-on light covering (it simply stays "as new" even after many yearss with no bubbles or sagging developing) and since tissue is not puncture resistant enough for such a model, I went for this which is basically nylon covering, hence extremely strong.

I have also used it on a 1/3 scale model. It's very light, very cheap, but requires some careful application per the instructions. If you are experienced with silk and tissue covering, and/or are prepared to learn this technique, I highly recommend it.

I also simulated rib stitching and rib tapes, using two layers of plaster tape from a pharmacy (I hope this is the correct English term for this, but you can see it in the picture), and some nylon fishing line for the "stitches", trapped between the two layers.
Then after application to the model, I added one more layer of tape slightly wider than the previous, and this was the "rib tape".

The important thing is to have the correct "pitch" of the stitches per the model scale. I think the real one has a pitch of 2" so I calculate based on this.

For paint - I brushed on polyurethane paint, since I have no spraying facility.
Use a good brush, well thinned paint (such that requires 3 coats just to see the pigment, and 6-7 coats in total...).
It isn't "Top Gun" quality but OK.

RE: Sig Miniplane - flat bottom or semi?
 

EF,

Very interesting and informative. Thanks so much for taking the time to share your process. It really came out looking great and appears very "REAL".

I spoke with a modeler at Joe Nall about his pinking tape, I believe it was on a red Fleet Biplane with about an 80" wingspan; absolutely gorgeous model. He used a prefabricated tape from a store in the U.S. called, I believe he said, Sallies Beauty Supply. This tape resembled real pinking tape and had a sticky adhesive on one side. It just happened to be sized right for his size model. I have not checked into this yet but will do so on my next project that has fabric covering.

Thank you,
Mike